Tamping tool



Jan. 30, 1934- H. s. BROWN TAMPING TooL Filed Dec. 7, 1931 2 Sheets-Sheet l Jan. 30, Y H. s BRQWN TAMPING TOOL K Filed Dec. 7, 1931 2 Sheets-Sheet 2 Patented Jan. 30, 1934 UNiTEo STATES PATENT ori-"1ct:A

TAMPING TOOL Hugh S. Brown, Harvey, Ill. Application December 7, 1931. Serial No. 579,398

13 Claims.

This invention relates to portable vibratory tools such as rock drills, tampers and other similar devices designed to be handled and by a single operator and carried by controlled him from place to place to the point of desired operation.

In devices of this character it is desirable that they consume as little power as possible, be

light in weight and operate with as little vibration I-Ieretofore it has been the practice as possible.

to provideV a massive vibrating hammer head and to actuate this head in one or both directions by some mechanical means frequently aided or partially restricted by some fluid means to increase or cushion the stroke of the hammer.

In Some instances purely pneumatic means have been used to actuate the driving element. In this latter type of device as made heretofore an external source of fluid under pressure was used as the driving means, which source had to be constantly renewed inasmuch as the compressed fluid was discharged after performing its work and a fresh working charge taken in for each stroke. In other words the fluid was put under suitable pressure by anexternal compressor and admitted at the desired pressure into a cylinder behind the hammer head. Disregarding a small amount of fluid trapped in the cylinder to cushion the return movement of the hammer head the entire working charge was renewed at each working movement of the piston.

I have discovered that the fluid usually entrapped and employed to merely cushion the hammer head may be employed as the sole means to impart working. movements to the hammer head by sealing one end of the cylinder and throwing a free hammer into the cylinder. this invention the hammer head itself According to is reciprocated or thrown up into the cylinder toward the sealed end to build up and impart a working pressure to a certain amount of entrapped air within the cylinder. Therefore no se parate air mit free return working movement of hammer. It has been found preferable the piston to provide a yielding or resilient drive for the cam to minimize the transmission of vibrations to and thence to the operator.

the casing (Cl. 12E-33) By my improvement many otherwise necessary working parts may be eliminated and the entire mechanism reduced to an extremely simple construction. Other novel features of this invention and their resulting advantages will be apv parent from the following description given in connection with the drawings in which:

Figure l is a vertical section through approximately the center of the vibratory tool omitting the working end of the tool member itself.

Figure 2 is the horizontal section taken on line 2-2, Figure l.

Figure 3 is a longitudinal transverse section through the operating or driving shaft and the elements carried thereby, illustrating the resilient drive for the cam, and

Figure 4 is a section takenv on line 4-4 on Figure 3.

Referring to the embodiment of this inventionillustrated in the drawings it will be seen that the entire mechanism with the exception of thev driving motor and the working end of the actuating tool itself is encased within a housing 1, formed at one side into an enlarged gear casing 2 closed by a cover plate 3. The casing proper is provided on one side thereof with a cylindrical housing 4 bored to receive a cylinder sleeve 5 which serves as a cylinder for the piston-like;

hammer head 6. The sleeve is held in position at one end by a cup-shaped bushing 7 received in an enlarged end of the cylindrical housing and is hermetically sealed atl its other end by a cap or head 8 securely held in position by cap screws 9 which also secure the handle 10 in place. Between the handle and the end of the cylinder may be inserted a pair of resilient discs 11 to absorb vibration and prevent transmission thereof to the operator. Cylinder sleeve 5 is ported as at 12 to the interior of the casing and to the atmosphere through a covered duct 13, the portsy 12 being located above the upper end of the piston when it is in its lowermost or outward position and preferably above the upper end of the i piston when in its highest position in contactwith the driving cam. Bushing '7 is provided with a hexagonal bore which serves as a bearing for the upper hexagonal end 14 of the vibrating tool 15. Bushing 7 is retained in place by an end cap 16 which also retains a rubber bumper 17 in position. A anged split bushing 18 serves as a guide or bearing for the projecting end of the vibrating tool and engages a shoulder 19'on the toolY uponvone side of its flanged end and also the rubber bumper 17 upon the other side of its flanged end and cooperates with the latter to return the tool to its upper position to be engaged by the piston hammer 6. For lubrication the cylindrical housing 4 is provided with a lubricant well 20 and the cylinder sleeve with ports 21 communicating therewith to conduct lubricant to the inner surface of the cylinder.

J ournalled transversely of the casing in spaced bearings 22 and 23 seated in cap 3 and in the opposite end of the casing respectively is a drive shaft 24, to one end of which is keyed a driving member or coupling 25 to which is keyed a gear 27. The gear and coupling are so disposed on the shaft that when the shaft is in position, gear 27 lies within gear casing 2. Coupling 25 terminates in a pair of diametrically opposite arcuate driving or arcuate clutch dogs 28 arranged to be nterlocked with and disposed between a similar pair of arcuate driving or clutch dogs 29 projecting from a driven member or coupling 30 journalled for rotation upon shaft 24 upon a bushing 26 inserted between the coupling and the shaft. Theinterlocking fingers 28 Vand 29 .permit only limited rotation of coupling 30 upon 'shaft 24 determined, of course; by the space between the opposed faces of the two sets of dogs. This permissible limited rotation of coupling 30 upon :shaft 24 `is .absorbed by four rubber or other resilient elements 31 disposed in cylindrical sockets formed in the opposed faces of the interlocking fingers. The rubber elements 31 areY of suicient resiliency to provide a yielding driving connection between the driving and driven elements and of sufficient density or hardness to prevent metal to metal contact of the two coupling members. The resilient members therefore absorb Vibrations which would otherwise be transmitted to the casing through the coupling 30 to the shaft upon operation of the device.

` `Projecting laterally from one side of coupling 30 and'formed integrally therewith is a laterally extending .projection or cam 32 having a substantially radially disposed impelling or striking surface 33a transverse to and intersecting the peripheral surface 33h of the cam, the irnpelling surface 33a being arranged to engage the lower or outer end -of piston hammer 6 when the latter is in its lowermost or outer position to throw the piston toward theclosed end of the cylinder upon rotation of shaft24.

A .driving motor 33 is strapped to the casing by -a strap 34 and carries a gear 36 which engages gear 27 for driving the latter and its shaft 24.

The operation of the tool is believed to be clear from the foregoing description and will therefore only be briefly summarized. Rotation of motor 33 will drive coupling 25 through gears 36 and 27. Gear '27 being keyed to coupling 25 will drive the latter with shaft 24. Coupling 25 will drive the .driven member or coupling 30 through 'the resilient elements 31 to rotate the cam 32. At'each rotation of cam 32 it will engage the end of vpiston hammer 6 and throw the latter toward upper or inner closed end of the cylinder. The .action of the cam is always the same regardless 'of wear upon the cam or piston end .because of the .particular cam employed. That is, the impelling surface is substantially radial as distinguished from the peripheral edge or surface and consequently the lift and Velocity of the cam'is constant `at any given speed of rotation of the shaft regardless of wear of the contacting surfaces of the cam and/or pistons. This upward movement of piston 6 will compress the 'air en- Ttrapped therein to a workingV pressure when -it will force piston 6 downwardly and cause it to strike a hammer blow upon the upper end 14 of the tool 15. As piston 6 clears ports 12 some of the entrapped air may escape and in any event the possibility of the formation of a partial vacuum is prevented. During the upward movement of piston 6 cam 32 has rotated one revolution and will again engage the lower end of piston 6 after it has delivered its working blow to the tool. It has been found that it is only necessary to construct and proportion the cam, piston and cylinder so that the cam throws the piston a part way only of its upper stroke permitting the inertia ofthe piston to complete its stroke while the cam retracts to be out of the way of the piston upon its downward stroke.

It will be observed from the foregoing description that no supply of fluid under pressure is necessary, and that the hammer is absolutely free within the piston and performs no work during its `downward stroke until it .strikes the hammer. The cylinder being ported vtothe atmosphere prevents the formation of any vacuum therein and furthermore does not permit of any lcompression of air upon its downward stroke, that is, no cushion is provided for the piston on its downward stroke. Furthermore, it is free to rebound and thereby delivers a sharp blow. Y

It will be obvious that minor changes .may be made in the details of construction without rdeparting from the .spirit and scope of the invention as defined in the following claims.

I claim: f

1. In a portable power vibratory tool, -a portable casing having .a cylinder therein .hermetically sealed at one .end and ported to the .atmosphere .at a point removed from said end, a piston hammer freely reciprocable in'said cylinder., va :shaft journaled in said casing and having a 'cam thereon arranged to engage said `pistonharnmer .and throw the latter toward theclosed end of said cyl'inderto compress .the entrapped air therein to a working pressure to .force vsaid piston hammer in a working direction the ports in 'said' cylinder being above the piston when .the latter is at its luppermost position in contact with the cam and .means carried by said Vcasing for rotating .said shaft.

2. .In Aa portable power vibratory tool, aportable casing havinga cylinder therein hermetically sealed at one end and ported to .the atmosphere at a point removed from said end, a piston hammer freely reciprocable .in said cylinder, a shaft journaled in said casing, a cam loosely mounted on said shaft `and yieldingly connected 'thereto arranged to engage `said piston hammer Land throw the latter due to its rotation and resilient .con

nection toward the closed end of said cylinderto compress the entrapped air therein Ito a working pressure vto force said piston hammer in a working direction and'means carried by said casing for rotating said shaft.

3. In a .portable power vibratory tool, .a portable casing havinga cylinder thereinhermetical-ly sealed at one end and ported to .the atmosphere ata point removed from said end, a .piston 'harnmer freely reciprocable in .said cylinder, a shaft journaled in said casingand having acam secured rac thereto for limited rotation upon said shaft arranged to engage said piston hammer and throw the latter toward the closed end of said .cylinder to compress the entrapped .air therein 'to a working pressure to force said piston hammer -in a werk ing direction, the ports in said cylinder 'beingabove the piston Ywhen the :latter is at its uppermost position and in contact with the cam, and 5i? means carried by said casing for'rotating said shaft.

4. In a portable power vibratory tool, a portable casing having a cylinder therein hermetically sealed at one end and ported to the atmosphere at a point removed from said end, a piston harnmer freely reciprocable in said cylinder, a shait journaled in said casing and having a cam thereon arranged to engage said piston hammer and throw the latter toward the closed end of said cylinder to compress the entrapped air therein to a working pressure to force sald piston hammer in a working direction, the ports in said cylinder being above the piston when the latter is at its uppermost position in contact with the cam, means carried by saidrcasing for rotating said shaft, and means for supporting a tool in position to be engaged by the end of said piston at substantially the limit of its working movement.

5. In a portable power vibratory tool a portable casing having a cylinder therein hermetlcally sealed at one end and ported to the atmosphere at a point removed from said end, a piston hammer freely reciprocable in said cylinder, a shaft journaled in said casing and having a cam thereon arranged to engage the end of said piston hammer and throw said piston hammer toward the closed end of said cylinder to compress the entrapped air therein to a working pressure to force said piston hammer in a working direction, the ports in said cylinder being above the piston when the latter is at its uppermost position in contact with the cam, and means carried by said casing for rotating said shaft.

6. In a portable power vibratory tool, a portable casing having a cylinder therein hermetically sealed at one end and ported to the atmosphere at a point removed from said end, a piston hammer freely reciprocable in said cylinder, a shaft journaled in said casing and having a cam yieldingly connected thereto and arranged to engage the end of said piston hammer and throw said piston hammer toward the closed end oi said cylinder to compress the entrapped air therein t-o a working pressure to force said piston hammer in a working direction, the ports in said cyiinder being above the piston when the latter is at its uppermost position and in contact with the cam, and means carried by said casing for rotating said shaft.

7. In a portable power vibratory tool, a portable casing having a cylinder therein hermetically sealed at one end and ported to the interior of said casing at a point removed from said end, a

i piston hammer freely reciprocable in said cylinder, a shaft journaled in said casing and having a cam thereon arranged to engage said piston hammer and throw the latter toward the closed end of said cylinder to compress the entrapped air therein to a working pressure to force said piston hammer in a working direction, the ports in said cylinder being above the piston when the latter is at its uppermost position in contact with the cam, and means carried by said casing for vrotating said shaft.

8. In a portable power vibratory tool, a portable casing having a cylinder therein hermetically sealed at one end and ported to the atmosphere at a point removed from said end, a piston hammer freely reciprocable in said cylinder, a shaft journaled in said casing and having a driving member rigidly secured thereto, a driven member journaled on said shaft, resilient driving connections between said driving and driven members,

v4said driven member having a cam thereon arranged to engage said piston hammer and throw the latter toward the closed end of said cylinder to compress the entrapped air therein to a Worxing pressure to force said piston hammerin a working direction, the ports in said cylinder being above the piston when the latter is at its uppermoet position and in contact with the cam, and means carried by said casing for rotating said shaft.

9. In a portable power vibratory tool, a portable casing having a cylinder therein heremetically sealed at one end and ported to the atmosphere at a point removed from said end, a piston hammer reciprocable in said cylinder, and means carried by said casing for intermittently raising said piston hammer to cause said hammer to compress the entrapped air in one end of said cylinder to a working pressure to force said piston hammer in working direction, the portsin said cylinder being above the piston when the latter is at its uppermost position in contact with said raising means.

10. In a portable power vibratory tool, a portable casing having a cylinder therein sealed at one end, a member adapted for reciprocatory movement in said cylinder and for compressing a resilient iiuid only during the final portion of its movement in said cylinder to produce the sole force to propel the member in the opposite direction with suicient energy to impart a working blow thereby, and means carried by said casing for intermittently moving the member positively through a portion only of its distance of movement into said cylinder and for throwing said member ree of said means for the remainder of the distance into said cylinder, the compressing of the iuid, during said nal portion, entirely taking place after the member leaves said means, said cylinder'being open to the atmosphere during the latter portion of the outward movement of said member and said member being free from mechanical and pneumatic restrictions during the latter portions oi' its outward movement.

11. In a portable power vibratory tool, a port-` able casing, a member adapted for reciprocatory movement in said casing and for compressing a resilient iuid only during the inal portion of its distance of movement in one direction to produce the sole force to propel the member in the opposite direction with suicient energy to impart a working blow thereby, a shaft journaled in said casing, and means driven by said shaft for intermittently moving the member positively through a portion only of its distance of movement in the rst-mentioned direction and for throwing said member freeof said means for the remainder of the distance in said direction, the compressing of the fiuid, during said final portion, entirely taking place after the member leaves said means. K

12. In a portable power vibratory tool, a portable casing, a member adapted for reciprocatory movement in said casing, and for compressing a resilient fluid only during the final portion of its distance of movement in one direction to produce the sole force to propel the member in the opposite direction with suiiicient energy to impart a working blow thereby, a shaft journaled in said casing and a cam having a contacting surface inclined to and intersecting the peripheral surface arranged to engage said member upon rotation of said shaft for intermittently moving said member positively through a portion only of its distance of movement in the first-mentioned direction and for throwing said member free of said cam for the remainder of the distance in said direction, the compressing of the fluid, during said final portion, entirely taking place after the member leaves said cam. y

13. In a portable power vibratory tool, a port-1 able casing, a member adapted for reciprocatory movement in said casing and for compressing a resilient fluid only during the nal portion of its distance of movement in one direction to produce the sole force to propel the member in the opposite direction with sufficient energy to impart a working blow thereby, a shaft journaled in s aid casing, and a cam having a substantially 

